In the past several years, the use of aircraft, and particularly of helicopters for work in the nature of police protection, aerial search and rescue, etc., has increased very rapidly. In many instances, it is necessary to use these craft at night in areas where there is little or no illumination. For example, it may be necessary to conduct a search and rescue for boaters at sea, campers in remote locations, etc. In such cases, it is usually necessary for the aircraft to be provided with a system by means of which the occupants can illuminate selected portions of the ground which is to be searched.
Such illumination devices sometimes consisted of hand-held lanterns or else floodlights which were rather difficult to control and focus. In this latter category, such structures often comprised lamps mounted on the exterior of the craft which could be controlled from the interior through complex linkages, cables, gear systems, etc. In most instances, control by the operator could be accomplished only with some difficulty in view of the fact that large displacements of the control device would result in small displacements of the lamps, or vice-versa. Consequently, it has often been difficult for an operator to accurately aim the lights, particularly when the aircraft was moving rapidly.
This prior art inability to accurately aim the light could be very dangerous. In cases in which armed criminals or escapees are being sought, it is necessary to aim the lights and turn them on only after they are aimed. If that sequence is followed, the chances of shots being fired at the aircraft are minimized. If the pilot or searchlight controller has a fairly good idea of where the criminal is on the ground, he is not providing a good target until he turns the light on.
Unfortunately, many prior art devices required that the searchlights be aimed by twisting a handgrip which resembles a motorcycle accelerator. This type of system allows only a "rough" aiming, at best, and little or no aiming accuracy can be achieved until after the lights are turned on. Consequently, it has become imperative for the aircraft occupants' safety, in such uses, that very accurate aiming of the searchlights be available prior to lighting the lamps.
Of course, with respect to hand held lights, it is somewhat easier to aim the light, much as one would aim a flashlight, but the degree of illumination of the surface achieved is significantly inferior. This results from the fact that the operator can normally operate only one or two rather small lamps due to the power required and the heat generated. Also, since the light rays must pass through the plastic or glass windows or hulls of the aircraft, the reflection of the light therefrom tends to blind the observer and make it much more difficult to see the surface area being searched.
Accordingly, it has become both necessary and desirable to provide an aircraft mounted searchlight system which will provide a maximum amount of surface illumination. Such a system should be very simple to maintain and operate, allowing the operator to quickly and accurately aim the lamps in a precise manner, even when the aircraft is moving at a high speed. Similarly, it is necessary that the device be used to operate exteriorly mounted lamps so that there will be no reflection of the rays emanating from the lamp into the cockpit, thus preventing the operator from being blinded by his own light. Of course, this desired result will also prevent the light level within the cockpit from becoming so great that it becomes difficult for the pilot to read his instruments.